President Barack Obama’s national security adviser said Sunday it would be a “grave mistake” for Russia to intervene militarily in Ukraine.

Susan Rice said on NBC’s “Meet the Press” that in Obama’s phone conversation with Russian President Vladimir Putin on Friday the two agreed that a political settlement in Kiev, the Ukrainian capital, should ensure the unity of the country and the right of Ukrainians to express their free will. She was asked whether the White House fears Putin will send Russian troops into Ukraine.

“That would be a grave mistake,” she said. “It’s not in the interest of Ukraine or of Russia or of Europe or the United States to see the country split.”

Protesters took to the streets of Kiev late last year after President Viktor Yanukovych abandoned an agreement that would have strengthened his country’s ties with the European Union in favor of seeking closer cooperation with Moscow.